Artificial tooth-crown



W. S. HOW.

ARTIFICIAL TOOTH CROWN.

Patented Nov. 6, 1883.

(No Model.)

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ARTI FICIAL TOOTH-CROWN.

SFECIFICATIN forming part of Letters llatentV No. 288,177, dated November 6, 1883.

Application filed April 12, 1883. (No model.)

Tooth-Crowns, or" which' the following is a specification.

My invention relates to artificialtoothcrowns for application to natural tooth-roots while in the mouth; and its. objects are to provide an improved crown, which may be readily applied to the root securely attached,.

and which will present an almost, if not quite, natural appearance when properly set.

The particular object of my improvement is to provide a crown which may be readily out or ground oii at its base at any required angle to suit the particular case in hand, and still be capable of secure and permanent attachment to the root.

The subject-matter claimed is particularly pointed out at the close ot' the specication.

In the accompanying drawings, Figure 1 is a verticallylongitudinal section through a root and crown, showing my improved crown as attached to the root; and 2 is a similar view of a modied form of crown for incisor' teeth. Fig. 3 is a similar section through one of my improved crowns, constructed for the replacement ofthe natural crown of a bicuspid tooth; and Fig. 4 is a similar view of a similar crown mounted. Fig. 5 is a similar section through a root and crown, the crown being modied by having the vertical post-opening therein extending all the way through the iucisor-crown. Figs. 6 and 7 are, respectively, a section of a modied incisor-crown having a spirally-luted post-opening, and' a bottom plan of abicuspidcrown of the same construction. Fig. Sis a central sectional view of a mold adapted for molding my improved crowns by means of a screw-plug.

The root A of the tooth is prepared in the usual or in any proper Ina-nner, for the reception of the crown B, which is to replace the natural crown, and said artiiicial crown is securely anchored to the root in` a well-known way, preferably by means of a screw or tooth post or posts, as clearly shown in Figs. l, 2, 4, and 5. The crown has a vertical post-opening, b, extending from its base into the body of the crown, but preferably not entirely through it, as shown invFigs. l, 2, 3, 4, 6, and 7. The opening, however, may extend through the crown, as shown in Fig. 5. This opening may be straight or tapered; but is preferably tapered from the base of the crown toward its face or cutting or grinding surface, as shown in Figs. l, 5, 6, and 7.

The interior surface ofthe walls ofthe crown- 6 opening is corrugated or provided with, .prefi erably, continuous or progressive retaining grooves or shoulders extending from at or near the base ofthe crown-well into the body thereof, or through it, if desired. Said corrugations or shoulders may be formed by annular threads or grooves, and said threads are preferably screw-threads or progressive threads, as clearly shown in Figs. '1, 2, 3, 4c, and 5; but a very desirable manner of forming this corrugation or series of grooves or shoulders is shown in Figs. Gand 7, where the interior walls ofthe post-opening are spirally iluted with the larger end of the spiral flutes at the base of the crown, as clearly shown in said figures. The corrugation ofthe inner walls of the crown is formed, preferably, by progressive or continuous grooves or shoulders, as above stated, and the projecting points of the shoulders may be either strictly angular, as shown in Figs. l, 3, and 5, or be formed by concave grooves, as shown in Figs. 2 and 4, or the shoulders or corrugations `may be formed by the convex spiral huizes, as shown in Figs. 6 and 7. By constructing the crown with the corrugations or series of grooves or shoulders extending from at or near the base ofthe crown-wellinto, and in seine cases through, the body thereof,

the crown may be cut or ground in different j while, when applied to the root, the crown the removal of the entire natural root from the mouth. In addition to this, the crowns may be cheaply and rapidly manufactured,

cannot be displaced under ordinary service.

Prior to applying the crown it is desirable that the outer end of the root to which the` vcrown is to be fitted should be Vslightly concaved or hollowed out, as clearly illustrated in the drawings, for the reception of the plastic securing material hereinafter mentioned.

In applying the crown the base of the crown v is cuty or ground to fit the particular shape of The retainingf screws are then securely tamped or screwedv the prepared end of the root.

in place in the root, and the crown is then filled with cement or amalgam-for example, such as that now commonly used by dentists for the purpose of securing artificial crowns to roots. The crown is then pressed to its place on the root with the pin, screw, or post entering or projecting into ythe post-opening of the crown, and as soon as the cement or amalgamy be lobvious to manufacturers and to dentistsfamiliar with the construction and application of artificial tooth-crowns to natural teeth.

)In Fig. 8 I have shown one way of making my improved crowns in a somewhat exaggerated form for better illustration. rIlhe plastic material or porcelain from which the crown is to be made is placed in the mold under an opening in one section of the mold, in which a plug screws back and forth. The plug has a forming point or end to correspond with thev shape to be given to the post-opening in the crown. In operation the plug is screwed down the proper distance in the crown to form the post-opening and corrugate its walls, and is then removed by a reverse motion, as will be obvious. A

- All the patentable matter disclosed and not particularly claimed herein is reserved as the subject-matter of a future application or applications which will be filed by me. v Prior to stating my claims it may be well to say that I am aware of the artificial toothcrown shown in the patent of Gates, dated March 1, 1881. That crown, however, has no progressive or continuous shoulders or corrugations, nor a series of annular grooves, and is not at all like my improved crown, and does not have its capabilities. The Gates crown has pits or grooves opposite each other, and two sets of such pits or grooves, oneat or near the base of the crown to constitute a retainother is near the top or in the coronal opening of the crown to retain the finalplug lorv stopper of amalgam, which is filled in from the top. cutaway to an extent to remove the pitted-or grooved part, which is very often required tin unfit for use, as it could not be securely fastened to the root, the upper set of pits being-too far removed from the place of joining to effect a secure attachment of the crown to the root.- With my improvement the crown can ybe cut away to any desired practical extent or at any angle, and there will be still left retaining-surfaces to secure the crown firmly to the root.

what I claim as new, and desire to secu-re by Letters Patent, is-- I. An artificialtooth-crown, having an opening extending from its base or neck into the body thereof, the interior walls of said opening being provided with a continuous longitudinally-curved or spiral `groove or shoulder ing well into the crown, substantially as `described. j

2. An articial tooth-crown -havingan open'- `ing extending from its base into thebody thereof, the inner walls of said opening bei-ng lar grooves commencing at or near the base of the crown and extending well into the body thereof, substantially as described.

In testimony whereof I have hereunto subscribed my name.

v VOODBURY S. HOW'.

Vitnesses: Y

J. A. B. WiLLIAMs, S. E. CAMPBELL.

Were the base ofthe Gates Vcrownl commencing at or near the base and extend-l corrugated or provided with a series of annuing-surface for the amalgam filling, while the I practical -operation,'the Gates crown would be Having thus fully described my invention, I

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